In the fabrication of integrated circuits, vapor deposition is one process used to form thin layers or films over a substrate. The term “vapor deposition” includes physical vapor deposition (PVD), chemical vapor deposition (CVD), or the combination of CVD and PVD (so-called “hybrid” physical-chemical vapor deposition). In a vapor deposition process, the substrate is exposed to a precursor gas, which deposits at the surface of the substrate or reacts at the surface of the substrate and deposits a product of the reaction thereon.